Equalizer for cranes.



No. 683,992. Patented Oct. 8, 190i.

H SAWYER EHUALIZEB FOR CRANES.

(Application filed May 14, 1897.)

(No Model.)

NITE TATES ATENT Fries.

HARRY SAIVYER, OF MUSKEGON, MICHIGAN, ASSIGNOR TO THE SHAW ELECTRIC CRANE COMPANY, OF SAME PLACE.

EQUALIZER FOR CRANES.

SPECIFICATION forming part of Letters Patent N 0. 683,992, dated October 8, 1901.

Application filed May l l, 1897- Serial No. 636,493. (No model.)

To aZZ whom it may concern.-

Be it known that I, HARRYSAWYER, a citizen of the United States, residing at Muskegon, in the county of Muskegon and State of Michigamhave invented certain new and useful Improvements in Equalizers for Cranes, of which the following is a specification.

My present invention relates to equalizers for cranes, and is designed to be used particularly in connection with cranes of large capacity, where it is necessary to support each end of the crane or bridge by four wheels, distributing the load equally upon all of them.

In the annexed drawings, Figure 1 is a perspective view of the equalizer; Fig. 2, a side elevation of the same; Fig. 3, a bottom plan View, and Fig. 4 a cross-sectional view on the line 1 1 of Fig. 2.

The object of my invention is to produce an equalizer capable of withstanding and distributing the strains to which it is subjected under varying loads, and this I accomplish by the composite structure hereinafter set forth.

The body portion of the structure is formed of cast-iron and comprises two sides or flange plates A A, connected by the intermediate section B, the whole being cast integral. In the lower flange or edge of each side plate or section A there is formed a channel or groove C, curved as shown in Fig. 2 and terminating in openings at each end upon the upper face of the body. Within these grooves or channels are placed bolts D, of wrought-iron, the ends protruding beyond the upper face at each end, and upon said ends are secured nuts by which the bolts or rods are placed under the desired degree of tension.

It is well known that cast-iron is very strong to resist compression, but comparatively weak in tension, while wrought-iron is strong in tension. The two metals are so combined that the compression strains are resisted by cast-iron,while the tension strains are divided between castdron and wroughtiron about in proportion to their strength. With a load only sufficient to put a tension in the lower section equal to the initial tension on the bolts no tension strains will come in the cast-iron. With greater load the excess puts a tension in both the cast-iron and the bolts in proportion to their moduli of elas ticity, which is about twelve million pounds per square inch for cast-iron and about twice that amount for Wrought-ironi The fiber stress in tension in the bolts when carrying a heavy load is therefore about twice the fiber stress in the cast-iron plus the initial tension in the bolts.

The side plates or sections are provided at their ends with suitable boxes or bearings E for the wheels. Other bearings for attachment to the bridge end and openings are also provided, these being formed and arranged as desired for each special case.

Having thus described my invention, what I claim is- 1. An equalizer for cranes comprising a cast-metal body, provided with a journalbearing ata point between its ends, and with an axle-bearing at each end, and wroughtrnetal trussing-bolts therefor, the bolts being placed under such tension as to produce a compressing strain upon the cast-metal body, substantially as and for the purposes set forth.

2. An equalizer for cranes comprising a cast-metal body provided with a journal or pivot bearing at a point between its ends and with an axle-bearing at each end, and having a curved lower face and wrought-metal bolts lying against the under face of said body and passing through the same near the ends thereof, said bolts being placed under such tension in the act of assembling as to effect a compression of the cast body and thereby to give to the bolts and the cast-metal elements fiberstresses in tension approximately proportionate to the ultimate strength of each.

3. In an equalizer for cranes, the combination of the side plates or sections A and the intermediate connecting-section B formed integral of castiron; grooves or channels formed in the lower edges of the sections A and terminating in openings upon the upper face; and wrought-iron bolts secured in said grooves under tension.

In Witness whereof I hereunto set my hand in the presence of two Witnesses.

HARRY SAWYER. Witnesses:

J. G. EMERY, J12, F. W. BABCOOK. 

